/**
* You can use this event display a custom help page
*
* @event core.faq_mode_validation
* @var string page_title Title of the page
* @var string mode FAQ that is going to be displayed
* @var string lang_file Language file containing the help data
* @var string ext_name Vendor and extension name where the help
* language file can be loaded from
* @since 3.1.4-RC1
*/

You can learn more about making an extension work with a core event here.